Fasteners such as nails and staples are commonly used in projects ranging from crafts to building construction. While manually driving such fasteners into a work piece is effective, a user may quickly become fatigued when involved in projects requiring a large number of fasteners and/or large fasteners. Moreover, proper driving of larger fasteners into a work piece frequently requires more than a single impact from a manual tool.
In response to the shortcomings of manual driving tools, power-assisted devices for driving fasteners into wood and other materials have been developed. Contractors and homeowners commonly use such devices for driving fasteners ranging from brad nails used in small projects to common nails which are used in framing and other construction projects. Compressed air has been traditionally used to provide power for the power-assisted devices. Specifically, a source of compressed air is used to actuate a piston assembly which impacts a nail into the work-piece.
The energy stored within the piston assembly is typically more than the amount of energy required to drive a nail or other fastener into a work piece. Accordingly, as the piston assembly reaches the end of a full stroke, a substantial amount of energy remains in the moving components of the piston assembly. A bumper is commonly located at the end of the piston assembly to arrest the moving components and to absorb the energy stored therein. Nitrile rubber is commonly used to fabricate such bumpers.
Nitrile rubber bumpers are very effective at absorbing the kinetic energy from the piston assembly. The heavy shock loads to which the bumper is subjected, however, ultimately results in wear and eventual disintegration of the bumper. Accordingly, the bumper component is prone to frequent failure and is one of the most frequently serviced components of a pneumatic nailer. A typical service life of a nitrile rubber bumper is on the order of 150,000 to 250,000 firings.
What is needed is a device incorporating an element which can be used to absorb kinetic energy from a drive mechanism. What is further needed is a device incorporating an element which is simple, reliable, lightweight, and compact. A further need exists for a device that incorporates a energy absorbing element that has a long useful lifetime.